The present invention relates to a video clamping circuit, and more particularly to a video clamping correction circuit for correcting distortion waves created in a video clamp circuit in a receiver for a satellite communication system signal composed of a video signal and an energy dispersal signal in the form of a triangle wave of 30 Hz, for example, which is superimposed on the video signal.
There have heretofore been employed peak clamping circuits such as diode clamping circuits for removing an energy dispersal signal superimposed on a video signal. Where the capacitance of a clamping capacitor is reduced in order to increase the rate of removal of the energy dispersal signal, the low-frequency characteristics become poorer, causing a clamped video signal output to suffer a waveform distortion.
Therefore, the rate of removal of the energy dispersal signal is incompatible with the waveform distortion of the video signal, and they have been compromised on a certain balanced basis. As an example, in case the waveform distortion is selected to be within 5%, the rate of removal of the energy dispersal signal is experimentally known as about 26 dB. Where an improved video clamping circuit as disclosed in U.S. patent application Ser. No. 484,193 filed Apr. 12, 1983 is employed, the removal rate of about 49.5 dB has experimentally been achieved with respect to the same waveform distortion of 5% or less. Although the removal rate has considerably been improved, the waveform distortion still remains unimproved, that is, within 5%.